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International team completes large survey of gas in nearby galaxies

SKA Global Headquarters, Thursday 18 May 2017 – An international team of investigators led by Dr. Claudia Cicone (INAF – Astronomical Observatory of Brera), Dr. Matt Bothwell (University of Cambridge) and with the SKA Organisation Project Scientist Dr. Jeff Wagg as principal investigator have found the spectra of the carbon monoxide emission line in a sample of small but nearby galaxies and found that the most massive galaxies form stars and are rich in metals.

The 12m APEX ESO telescope, located on the plateau of Chajnantor in Chile, at 5000m altitude.

The team, comprising investigators from Italy, the UK, Germany, Chile and China have completed a large survey of molecular gas in nearby galaxies using the 12m APEX telescope in Chile. The APEX Low-redshift Legacy Survey of MOlecular Gas (ALLSMOG, PI: Dr. Jeff Wagg) has observed the Carbon Monoxide (CO) molecule in a sample of 97 galaxies in the local Universe. The ALLSMOG data provide important information on the cold molecular gas content of these galaxies which have been well characterised in terms of their star-formation rates, gas-phase metallicities and atomic HI gas masses.

ALLSMOG is an ESO observing program conceived by Dr. Jeff Wagg to study the molecular gas through the carbon monoxide emission line with the telescope Atacama Pathfinder Experiment (Apex), a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (Oso) and ESO, which is located on the plain of Chajnantor at 5000 meters above sea level, in the Chilean Andes.

The article ” The final release date of ALLSMOG: a survey of CO in typical local low-M star-forming galaxies ” published today in the journal Astronomy & Astrophysics includes observations of 97 galaxies, 88 of whom studied with Apex (for more than 300 hours of observation from summer 2013 to winter 2015/2016) and 9 with the telescope of the Institute of millimetric radio astronomy (Iram) to Pico Veleta, Spain (between 2014 and 2015). The survey is the first major campaign ALLSMOG systematic observation of carbon monoxide extragalactic made with Apex telescope.

“The ALLSMOG survey is the first large systematic extragalactic survey of CO ever conducted with the APEX telescope”, says Claudia Cicone, a Marie Skłodowska-Curie fellow at INAF- Osservatorio Astronomico di Brera. “Our research has an enormous legacy value because the entire scientific community can exploit our data. We really hope our efforts will stimulate new ideas and results.”

“For all the galaxies in our sample we have additional information on their physical properties from optical observations and on their atomic gas content (HI) from radio observations of the HI21cm line published in previous studies and by other teams. We have created a real identikit of these galaxies which allows us to study the relations between the molecular gas and their other physical properties.”

“In the near future, multi-wavelength galaxy studies like this will be greatly enhanced by data from the SKA telescope and its precursors such as ASKAP and MeerKAT”, says Dr. Jeff Wagg. “While the SKA precursors are expected to detect more than half a million galaxies in HI line emission, these sample sizes have the potential to increase by nearly an order of magnitude when the SKA1-mid telescope comes online.”

SKA1-mid is the dish array telescope to be built in South Africa that will be operating in the 350Mhz -14Ghz frequency range, complementary to the low-frequency telescope (so-called SKA1-low) to be built in Australia. Although SKA1-mid and the SKA precursors do not have the frequency coverage needed to measure the molecular gas in nearby galaxies, they will be able to detect the atomic gas through the 21cm atomic HI line transition.

“Quantifying the total gas content (atomic and molecular) of significant samples of galaxies out to large distances remains one of the crucial elements needed for a full understanding of galaxy formation”, concludes Dr. Jeff Wagg.